As a result, most leases are concluded in writing, with the rights and obligations of each party clearly stated. Instead, the entire arrangement is made on the basis of an email exchange and/or oral agreement. In most cases, things are going pretty well. Owners of real estate built before January 1, 1949 must also attach a CREP (Risk of Lead Exposure) report indicating the risk of lead poisoning in the building. This CREP must be available to any new or renewed lease. Although the law recognizes a lease that is concluded orally, in the event of a dispute, only the bare minimum of clauses is accepted by a court. While there is some freedom for landlords and tenants to vary and add clauses, some clauses are expressly prohibited in a rental agreement.